Investigation on Film Cooling Performance of a Novel Hole Arrangement Based on Combined-Hole Design

Based on a combined-hole design, a novel hole arrangement was proposed and tested on a flat plate model by numerical simulation. Replacing one row in two rows of staggered holes with a row of smaller holes, the bigger holes in one row and smaller holes in the other row will form combined-hole units. The kidney–vortex pairs in the combined-hole unit will interact with each other and get weakened, finally enhancing film cooling performance. Compared to the original two rows of staggered holes, the coolant mass flowrate will be reduced by 25% for the new hole arrangements. Results show that the area-averaged film cooling effectiveness of the new arrangements is similar or even higher than that of the original one at different blowing ratios. Replacing the second row of holes with smaller holes provide better cooling performance than replacing the first row of holes. The overall film cooling performance is not sensitive to the row space. The highest improvement of film cooling effectiveness is 24% when the blowing ratio is 1. However, as the coolant accumulation and reattachment phenomenon is weakened by the new arrangements, the film cooling performance is not as good as the original one when the blowing ratio is 1.5.